KR101961834B1 - Method of fabricating a led display apparatus - Google Patents

Abstract

According to one embodiment of the present invention, provided is a manufacturing method for an LED display device, comprising: a step of providing a plurality of LED structures each of which has an LED chip and a polymer extension part applied to the LED chip; a step of aligning the plurality of LED structures in the desired areas of the display panel, separately; and a step of removing the polymer extension part from the plurality of LED structures.

Description

METHOD OF FABRICATING A DISPLAY APPARATUS [0001]

The present invention relates to a method of manufacturing an LED display device and a LED structure used therefor.

In the field of displays, inorganic (eg, semiconductor) based light emitting diode (LED) displays are gaining popularity as well as organic EL (organic electro luminescence) displays. In recent years, semiconductor light-emitting diodes have been manufactured to be as small as a few tens of micro-degrees to overcome the inherent problems (such as brittleness) of inorganic materials and show possibility of expansion of new display devices such as flexible display and curved surface display.

In order to realize this, there is a need for a transfer process capable of placing micro-sized (e.g., several hundreds 탆 or less) LED chips on a desired substrate (e.g., flexible substrate) in a desired arrangement. In the case of the currently designed wafer level transfer process, the distance ratio between the chips is limited to a 1: 1 arrangement and can be useful for some high resolution displays (eg AR or VR). However, there is a problem that the wafer level transfer process can not actively cope with defects or wavelength variations of some chips in the wafer.

On the other hand, it is possible to implement a variety of 1: N arrangements of display devices by using a pick-and-place process for individual LED chips. However, since the transfer process such as the pick-and-place process is performed on an individual LED chip basis, the process is extremely inefficient (e.g., millions of processes are required), which results in a long process time and low yield.

One of the problems to be solved by the present invention is to provide an LED chip transfer method capable of easily transferring a micro-sized LED chip to a desired position, and a method of manufacturing an LED display device using the same.

One embodiment of the present invention is directed to a method of manufacturing a display device, comprising: providing a plurality of LED structures each having an LED chip and a polymer extension applied to the LED chip; aligning the plurality of LED structures in desired areas of the display panel, And removing the polymer extensions from the plurality of LED structures.

For example, the polymer extensions may surround the LED chip such that the surface of the LED chip on which the electrodes are formed is exposed.

Each of the desired regions may be provided with a circuit pattern, and the step of aligning the plurality of LED structures may include aligning the plurality of LED structures such that the exposed electrodes are positioned in the circuit pattern.

In this case, an electrode connecting conductor is disposed on at least one surface of the electrode and the circuit pattern, and after the step of removing the polymer extensions, melting the electrode connecting conductor so that the electrode is connected to the circuit pattern .

For example, at least one of the electrode and the circuit pattern of the LED chip may have magnetism so that electrodes of the LED chip are aligned on the circuit pattern in the step of aligning the plurality of LED structures.

In one example, the desired regions may have a concave structure for aligning the plurality of LED structures.

In one example, in aligning the plurality of LED structures, the polymer extensions and the desired regions may be self-assembled monomers so that the LED structures are each aligned with the desired regions.

For example, after forming the plurality of LED structures, the step of arranging the plurality of LED structures may include a step of arranging the plurality of LED structures by using a jetting method And aligning the plurality of LED structures together with the solvent.

As an example, aligning the plurality of LED structures may be performed using a sieve in which the desired regions are open.

For example, the polymer extender may have a spherical shape and may have a diameter greater than the length of the LED chip.

Alternatively, the polymer extensions may have a non-spherical shape, and in the step of aligning the plurality of LED structures, the desired regions may each have a concave structure for receiving the non-spherical shape such that the plurality of LED structures are aligned.

For example, the polymer extensions may have a width and height greater than the length of the LED chip.

In one embodiment, the polymer extensions include a polymer that is capable of calcining at a temperature of 300 ° C or less, and the step of removing the polymer extensions may include heating to the calcineable temperature.

According to an embodiment of the present invention, there is provided a method of manufacturing an LED, comprising: providing an LED structure including an LED chip having electrodes on at least one side thereof and a polymer extension portion having a three-dimensional structure surrounding the LED chip, Aligning the LED structure in a mounting area where a circuit pattern is formed, the electrodes of the LED chip being disposed on the circuit pattern; and after the step of aligning the LED structure, heating the LED structure so that the polymer extender is calcined The method comprising the steps of:

For example, an electrode connecting conductor is disposed on at least one surface of the electrode and the circuit pattern, and after the heating of the LED structure, the electrode connecting conductor is melted so that the electrode is connected to the circuit pattern .

As described above, the micro LED chip can be easily transferred to a desired area (particularly, a sub-pixel) of the display panel by providing an expanding part using a polymer that can be calcined. The expansion part made of a polymer ), A simple calcination process can be eliminated. In particular, the polymer extensions can be easily aligned using various methods by employing spherical or partially spherical shapes.

1 is a flowchart illustrating a method of manufacturing an LED display device according to an embodiment of the present invention.
2A and 2B are cross-sectional views for explaining a manufacturing process of an LED structure that can be employed in an embodiment of the present invention.
FIG. 3A is a cross-sectional view of the semiconductor light emitting diode chip shown in FIG. 2A, and FIG. 3B is a cross-sectional view of the LED structure shown in FIG. 2B.
Figure 4 schematically depicts a solvent containing LED structures.
5 is a plan view showing an LED display device according to an embodiment of the present invention.
6A to 6G are cross-sectional views illustrating a method of manufacturing an LED display device according to an exemplary embodiment of the present invention.
7 is a perspective view showing an example of a LED structure that can be employed in an embodiment of the present invention.
8 is a perspective view showing a mold used for manufacturing the LED structure shown in Fig.
9A and 9B are a plan view and a cross-sectional view, respectively, showing an example of a LED structure that can be employed in an embodiment of the present invention.
10A and 10B are cross-sectional views showing various examples of LED chips that can be employed in an embodiment of the present invention, respectively.
11A and 11B are a plan view and a cross-sectional view, respectively, showing an example of a LED structure that can be employed in an embodiment of the present invention.
12A to 12E are cross-sectional views for explaining a method of transferring an LED chip according to an embodiment of the present invention.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments may be modified in other forms or various embodiments may be combined with each other, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments are provided so that those skilled in the art can more fully understand the present invention. For example, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements. Also, in this specification, terms such as "upper", "upper surface", "lower", "lower surface", "side surface" and the like are based on the drawings and may actually vary depending on the direction in which the devices are arranged.

The term " one example " used in this specification does not mean the same embodiment, but is provided to emphasize and describe different unique features. However, the embodiments presented in the following description do not exclude that they are implemented in combination with the features of other embodiments. For example, although the matters described in the specific embodiments are not described in the other embodiments, they may be understood as descriptions related to other embodiments unless otherwise described or contradicted by those in other embodiments.

1 is a flowchart illustrating a method of manufacturing an LED display device according to an embodiment of the present invention.

First, the manufacturing method of the LED display device according to the present embodiment may start with the step S11 of providing a micro LED chip (see FIG. 3A).

As used herein, the term " micro-LED chip " refers to an LED chip having a micro-unit size, for example, a length of one side having a relatively long length of 500 mu m or less, Of LED chips.

The micro LED chip can be used as a light source for a pixel (especially a sub-pixel) of a display device. The micro LED chip may be an LED chip having an active layer emitting a wavelength in a visible light band. For example, red, green, and blue LED chips.

The micro LED chip is a semiconductor LED chip obtained by forming a semiconductor epitaxial on a wafer. For example, the micro LED chip is made of Al _x In _y Ga _(1-xy) N (0 <x <1, 1, 0 <x + y < 1), Al x In y Ga (1-xy) P (0 <x <1, 0 <y <1, 0 <x + y <1), Al x In y Ga ( _1-xy) As (0 < x < 1, 0 < y < 1, 0 < x + y < 1).

Since the micro LED chips used in the present invention are individually transferred (e.g., in units of subpixels), the LED chips of each color (each subpixel unit) are formed by using different epitaxial growth processes in different wafers without a separate wavelength conversion layer Can be prepared in advance.

Further, in the process of preparing the micro LED chip, after the optical characteristic of the micro LED chip is measured, the defective chip can be removed or a binning process according to the emission wavelength can be performed. Even when fabricated on the same wafer to obtain a single-color LED chip, the wavelength may vary slightly depending on the wafer area. Therefore, it is possible to classify the LED chips more precisely by measuring the emission wavelength in advance, and to provide a color of a more accurate wavelength in each sub-pixel.

Next, in step S13, a polymer extension is formed in the micro LED chip to provide a LED structure having a polymer extension (see FIG. 3B).

By applying the liquid polymer to the micro LED chip to form the polymer extension, the micro LED chip can be easily handled in the subsequent alignment process and the micro LED chip can be protected by the polymer extension. In another example, the polymer extensions may have the shape of another three-dimensional structure. For example, a desired three-dimensional shape can be produced using a mold structure (see FIG. 7). Such a three-dimensional shape may be a structure corresponding to the groove shape so as to be easily arranged in the groove of the subpixel. For example, it can be formed into a hemispherical or inverted structure (a structure having a lower surface than an upper surface) (see Figs. 8 to 9B).

A specific example of this process will be described later with reference to Figs. 2A and 2B. The size of the polymer extensions can be controlled by the dropping amount of the polymer.

The material that constitutes the polymer extender is selected by a simple process to remove the material. For example, a polymer material that can be calcined at a relatively low temperature (e.g., 100 to 300 캜) can be used. Preferably, a polymer material that is capable of being calcined at a temperature lower than the temperature that is applied when the electrode of the LED chip is bonded to the circuit pattern (e.g., a reflow process) may be used. On the other hand, the constituent material of the polymer extender may be a polymer in which almost no optically-influencing residual material is present.

In one example, the polymer extensions may be formed of polystyrene or polymethyl methacrylate (PMMA). For example, the polymer extensions, which are polystyrene, can be calcined at a temperature of about &lt; RTI ID = 0.0 &gt; 145 C &lt; / RTI &gt;

Next, in step S15, the LED structure can be aligned on the display panel.

Various methods using the polymer extender can be utilized in this alignment process. For example, a LED structure can be placed in a desired area (e.g., a sub-pixel) using a jetting or sieve such as an inkjet.

In addition, a variety of self-aligning processes can be utilized for precise alignment (e.g., placing the electrodes on the circuit pattern) in the desired area. In one example, a self assembly monomer can be used to treat the surface of the polymer extensions and the surface of the area in which the LED structure is to be placed to be hydrophobic and / or hydrophilic. In another example, the area of the subpixel may be formed in a concave structure and the size and shape of the concave structure may be arranged to be aligned in the process of insertion of the polymer extensions or LED structures (see FIGS. 12B and 12C). In another example, the LED structure can be accurately aligned using magnetism. Specifically, at least one of the electrodes and the circuit pattern of the LED chip may be configured to have magnetism so that the electrodes of the LED chip are aligned on the circuit pattern.

The above-described alignment process can be used alone, but can be combined with each other to realize more effective alignment. For example, it is possible to arrange the LED structure in a subpixel using an inkjet process, and more precise alignment can be realized so that the electrode of the LED chip is located on the circuit pattern using the concave structure or the magnetism of the subpixel.

Then, in step S17, the polymer extensions are removed from the micro LED chips.

It is possible to uniformly apply the step of removing the polymer extensions after arranging them all in the desired subpixels. In this process, only the micro LED chips remain and can be disposed on the sub-pixel region (e.g., a circuit pattern). The process of removing such polymer extensions may be performed by heating to an appropriate temperature as described above. The heating temperature in this step can be selected to be lower than the melting point of the electrical connection conductor (e.g., solder) disposed on the electrode.

The electrode shape of the micro LED chip and the circuit pattern located in the sub pixel can be variously changed in the design of the electrode and the circuit pattern so as to be easily connected to each other. Further, as described above, when the electrodes and / or the circuit pattern are magnetized or the SAM process is used, after the process of removing the polymer extensions, the electrode of the micro LED chip is repositioned .

Next, in step S19, the micro LED chip is bonded to the circuit pattern of the subpixel.

The LED chip can be bonded to a desired location (e.g., a sub-pixel) by melting (e.g., reflowing) the electrical connecting conductor located on the electrode or circuit pattern of the micro LED chip. In the case where the electrodes are vertical-type LED chips located on opposite sides positioned opposite to each other, a desired display device can be manufactured by forming additional wiring on the upper-positioned electrode.

2A and 2B are cross-sectional views for explaining a manufacturing process of an LED structure that can be employed in an embodiment of the present invention. FIG. 3A is a sectional view of the semiconductor light emitting diode chip shown in FIG. 2A, Sectional view of the LED structure shown.

It can be understood that the cross section shown in Figs. 2A and 2B is represented by the process corresponding to the steps 11 and 13 shown in Fig.

Referring to FIG. 2A, a micro LED chip 50 may be arranged on the temporary support 10. FIG.

The micro LED chip 50 may be arranged such that the surface on which the electrode 57 is formed faces downward. The electrode 57 in contact with the temporary support 10 may further include an electrical connection conductor such as a solder bump as a bonding electrode.

The LED chip 50 adopted in the present embodiment may be a vertical structure in which two electrodes 57 and 58 are located on opposite sides, as shown in Fig. 3A. Of course, in another example, a horizontal structure LED chip in which two electrodes are arranged on the same plane may be used (see Figs. 10A and 10B).

Referring to FIG. 3A, an LED chip 50 employed in this embodiment is shown. The LED chip 50 includes a conductive substrate 51 and a semiconductor epitaxial layer 55 disposed on the conductive substrate 51. The semiconductor epitaxial layer 55 includes a laminate including first and second conductivity type semiconductor layers 55a and 55c and an active layer 55b disposed therebetween. The first and second electrodes 57 and 58 may be connected to the conductive substrate 51 and the second conductive type semiconductor layer 55c, respectively.

The first and second conductivity type semiconductor layers 55a and 55c may be p-type and n-type semiconductor layers, respectively, and may be a nitride semiconductor, for example, Al _x In _y Ga _(1-xy) x <1, 0 <y <1, 0 <x + y <1). Of course, it may be a GaAs-based semiconductor or a GaP-based semiconductor in addition to a nitride semiconductor. The active layer 55b formed between the first and second conductivity type semiconductor layers 55a and 55c may be configured to emit light of a predetermined wavelength. For example, the active layer 55b may have a multiple quantum well (MQW) structure in which quantum well layers and quantum barrier layers are alternately stacked. In the case of a multiple quantum well structure, for example, it may be InGaN / GaN, AlGaN / GaN structure.

Next, referring to FIG. 2B, an appropriate amount of liquid polymer is dotted on the micro LED chip 50 using a dispensing process to form a polymer extension 60.

The polymer extensions 60 may have a generally spherical shape (e.g., ball type) that is easy to handle. Such spherical polymer extensions 60 utilize the surface tension of the liquid polymer, and thus can be manufactured simply without a separate mold structure. The LED structure 80 formed in this process is shown enlarged in Fig. 3B. Referring to FIG. 3B, a surface of the micro LED chip 50, that is, a surface on which the first electrode 57 is formed, may be exposed on one side of the polymer extension 60. In the process of disposing the LED structure 80 in a desired region (e.g., a subpixel), the exposed first electrode 57 may be in contact with a circuit pattern located in the subpixel.

As a method of storing or aligning the LED structure, a solvent containing the LED structures may be used, as shown in FIG.

Referring to FIG. 4, a non-reactive solvent 90 in which a plurality of substantially spherical LED structures 80 are dispersed is contained in a container V. The solvent 90 containing the LED structure 80 may be used in an alignment process using a jetting and sheave, such as storing the LED structure 80 or inkjet. The non-reactive solvent may be a solvent that does not substantially react with the polymer extender, and a solvent that hardly reacts with other elements of the display panel (e.g., circuit patterns, etc.) when utilized in the alignment process. For example, when the polymer extender is made of polystyrene, an organic solvent free of benzene groups may be used, and a non-polar solvent such as ethanol may be used because it reacts with a polar solvent when the polymer extender is formed of PMMA.

The jetting process using the solvent 90 containing the LED structure 80 may be performed by mixing the LED structure 80 and injecting the desired mixture into the desired area. The LED structure 90 is selectively disposed on each subpixel in such a manner that the solvent 90 containing the LED structure 80 is poured onto the sheave in the case where the region to which the specific subpixel is selectively used is used (See FIG. 6C).

FIG. 5 is a plan view showing an LED display device according to an embodiment of the present invention, and FIGS. 6A to 6G are cross-sectional views illustrating a method of manufacturing an LED display device according to an embodiment of the present invention. Here, Figs. 6A to 6G each show an I-I 'portion of the LED display device shown in Fig.

Referring to FIG. 6A, a display substrate 110 on which a circuit pattern 115 is formed is provided. Referring to FIG. 6B, the barrier rib structure defining the first through third sub-pixels S1, S2, 120 are shown.

The display substrate 110 may be a TFT substrate including a thin film transistor (TFT). The display substrate 110 includes circuitry configured to independently drive each of the first through third sub-pixels S1, S2, and S2. The circuit pattern 115 includes sub-pixels S1, S2, and S2, respectively. The first through third sub-pixels S1, S2, and S3 may be provided as regions providing red, green, and blue light, respectively.

Referring to FIG. 5, the first through third sub-pixels S1, S2, and S2 are repeatedly arranged along a row, but the present invention is not limited thereto. In other embodiments, The subpixels may be arranged in a known arrangement.

6B, the barrier structure 120 disposed on the display substrate 110 provides a recess C for receiving the LED structure 80. As shown in FIG. The concave portion C can be set in consideration of the shape and the size of the LED structure 80.

The barrier structure 120 employed in this embodiment may be a light blocking structure such as a black matrix. The black matrix is not limited to a black color, and may be used in other colors such as a white matrix or green if necessary, and the white matrix may further include a reflective material or a scattering material.

Although the barrier structure 120 employed in this embodiment is illustrated as a light shielding structure of each pixel in the final product, in another embodiment, the barrier structure 120 is used only as a structure providing a recess for arranging the LED structure, After the completion of the bonding process (see FIG. 6F), the barrier structure may be removed and a new light blocking structure may be introduced.

Referring to FIG. 6C, the LED structure 80 may be aligned on the display substrate 110 using a sheave 130. FIG.

The sheave 130 employed in the present process has a structure in which only the first sub-pixel S1 is selectively opened and the other second and third sub-pixels S2 and S3 are blocked. Thus, as shown in FIG. 6C, the first LED structure 80R through such a sheave 130 can be accurately arranged in the concave portion C of the first sub-pixel S1. For example, the first sub-pixel S1 may be a red pixel and the first LED structure 80R may include a red LED chip 50R.

As described above, the shape and size of the concave portion C can be set according to the LED structure. For example, the width w of the recess C may be somewhat larger than the diameter d2 of the polymer extensions 60 so that the first LED structure 80R can be easily accommodated. However, when the deviation between the width w of the concave portion C and the diameter d2 of the polymer extension portion is excessively large, accurate alignment of the first LED structure 80R in the concave portion C may be difficult, Can be suitably limited.

The height H of the barrier rib structure 120 does not need to be greater than the height of the first LED structure 80R and is less than the height of the first LED structure 80R, A height that can be guaranteed is sufficient. For example, the barrier structure 120 may be at least about 50% of the height of the first LED structure 80R.

Additional self-aligning processes can be combined in this process. For example, the self-alignment monomer (SAM) may be used to treat the polymer extender 60 and the bottom surface of the subpixel as hydrophobic and / or hydrophilic, or the electrode 57 of the LED chip 50 and the circuit pattern 115 may provide magnetism to achieve accurate alignment taking into account the electrode location.

Next, referring to FIG. 6D, by repeating the process similar to the process shown in FIG. 6C by replacing another sheave, the concave portion C of the second and third sub-pixels S2 and S3 is also changed The second and third LED structures 80G and 80B, respectively.

The other sheaves used in this process have a structure for selectively opening the regions of the second and third sub-pixels S2 and S3, respectively. Second and third LED structures 80G and 80B having green and blue LED chips 50G and 50B may be arranged in the second and third subpixels S2 and S3, respectively. The second and third LED structures 80G and 80B employed in this embodiment may have similar polymer extensions 60. [ In addition, this process can also combine additional self-aligning processes (e.g., using SAM or magnetic) similar to the previous process. Of course, in another embodiment, the concave portion of each sub pixel region and each LED structure may be formed in different shapes so that only the corresponding LED structure is accommodated in the concave portion of each sub pixel.

Next, referring to FIG. 6E, the polymer extension 60 is removed from the micro LED chip 50.

The process of removing the polymer extensions 60 can be uniformly performed on the LED structures 80R, 80G, and 80B disposed in the entire sub-pixels S1, S2, and S3. In this process, only the micro LED chip 50 remains and can be disposed on a sub-pixel region (e.g., a circuit pattern). The present process can be carried out by heating to an appropriate temperature. After the polymer extensions are removed, the micro LED chips 50R, 50G, and 50B may be additionally and partially reordered by other self-aligning elements (e.g., SAM or magnetic), but are not so limited.

Next, referring to FIG. 6F, a reflow process for bonding the micro LED chip 50 to the sub-pixel circuit pattern 115 is performed.

This process can be uniformly performed on the LED chip 50 disposed in the entire sub-pixels S1, S2, and S3 similar to the polymer extender removal process described above. In this process, the electrode 57 'of the micro LED chip 50 can be melted on each circuit pattern 115 and bonded to a desired position (for example, a circuit pattern of a sub pixel). 6D, when the electrodes 57 are relatively accurately aligned with the desired circuit pattern 115, the process of removing the polymer extensions 60 and the reflow process may be performed simultaneously or sequentially It is possible.

Next, referring to FIG. 6G, a desired display device can be manufactured by forming a separate wiring 140 on the second electrode 58 located on the upper side.

Such a wiring 140 may be formed of a transparent electrode such as ITO so as to have no optical influence. The insulating layer 130 may be additionally formed in the concave portion so that the second electrode 58 is opened to form the wiring 140. The insulating layer 130 may be formed of a material such as silicon oxide, silicon nitride, or other polymer.

Unlike the present embodiment, in the case where the electrodes are LED chips of a flip chip structure rather than vertically arranged LED chips located on opposite sides, the connection between the LED chip and the circuit pattern can be completed by the preceding bonding process (Figs. See Fig. 12E).

The LED structures that can be employed in the present invention may have various shapes depending on the shape of the polymer extensions. Various examples of LED structures that can be employed in an embodiment of the present invention are illustrated in Figs. 7, 9, and 11. Fig.

Referring first to FIG. 7, the LED structure 80 'according to the present embodiment may have a partially spherical or hemispherical polymer extension 60'.

The side surface SP of the polymer extension 60 'has a curved surface obtained from a spherical shape, so that it can be easily inserted into the concave structure of the sub pixel similarly to the polymer extension 60 according to the previous embodiment. While the top surface (TP) of the polymer extensions may have a substantially planar surface. The insertion into the concave structure can be easily induced by using the squeeze structure through the upper surface TP.

The polymer extensions of the spherical three-dimensional structure can be formed using a mold. 8 is a perspective view showing a mold used for manufacturing the LED structure shown in Fig.

Referring to Fig. 8, a mold 200 having a plurality of mold holes MC of a desired shape (e.g. hemispherical) is shown. The LED chip structure 80 'shown in FIG. 7 can be manufactured by disposing the LED chip 50 in each molten metal hole MC, filling the mold hole MC with the liquid polymer, and curing it.

Although the above-described examples of the LED structure are exemplified as including a vertically-structured LED chip, they may be similarly applied to a horizontal-type LED chip such as a flip chip structure. In the case of the LED chip having the flip chip structure, the surface on which the two electrodes are formed may be exposed from one side of the polymer expansion part to the outside.

Unlike a vertical LED chip, a flip chip LED chip requires alignment of two electrodes to two different circuit patterns in a mounting scene, thus requiring more precise alignment. This exact arrangement can be implemented using an asymmetric structure of the polymer extensions. These embodiments will be described with reference to Figs. 9 to 11. Fig.

9A and 9B are a plan view and a cross-sectional view, respectively, showing an example of a LED structure that can be employed in an embodiment of the present invention.

9A and 9C, the LED structure 80A according to the present embodiment includes an LED chip 50A having a flip chip structure and a hemispherical polymer extension 60A similar to the polymer extension 60 ' ).

However, unlike the polymer extensions 60 'of FIG. 7, the polymer extensions 60A employed in this embodiment have an asymmetric structure with one side cut off CP. The cut surface CP is located at one side of the polymer extension 60A along the arrayed direction of the two electrodes 59a, 59b of the LED chip 50A (which may be electrical connection conductors). Therefore, the cut surface CP not only indicates the direction in which the electrodes are arranged, but also can ensure a more accurate alignment process. Specifically, by designing the concave structure of the sub-pixel to correspond thereto, the LED structure 80A can be aligned such that the arrangement of the electrodes 59a and 59b of the LED chip 50A coincides with the predetermined arrangement of the circuit patterns 12b and 12c).

10A and 10B are cross-sectional views showing various examples of LED chips that can be employed in an embodiment of the present invention, respectively.

The LED chip 50A shown in Fig. 10A may include a light-transmissive substrate 51 and a semiconductor epitaxial layer 55 disposed on the light-transmissive substrate 51. Fig.

The light-transmitting substrate 51 may be an insulating substrate such as sapphire. However, the present invention is not limited thereto, and the substrate 51 may be a conductive or semiconductor substrate that can ensure light transmission in addition to an insulating substrate.

The semiconductor epitaxial layer 55 may include a first conductive type semiconductor layer 55a, an active layer 55b, and a second conductive type semiconductor layer 55c sequentially disposed on the light-transmitting substrate 51 . The structure of each layer can be referred to the description of FIG. 3A.

The first and second electrodes 58a and 58b are formed on the same plane so that the mesa-etched region of the first conductivity type semiconductor layer 55a and the mesa-etched region of the second conductivity type semiconductor layer 55c Respectively. For example, the first electrode 58a may include at least one of Al, Au, Cr, Ni, Ti, and Sn. The second electrode 58b may be formed of a reflective metal. For example, the second electrode 58b may include a material such as Ag, Ni, Al, Cr, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Structure. The first and second electrodes 58a and 58b may include first and second electrical connection conductors 59a and 59b, respectively. The first and second electrical connection conductors 59a and 59b may include conductive bumps such as solder and may be formed of a conductive material such as Au, Ag, Al, Ti, W, Cu, Sn, Ni, Pt, Cr, NiSn, TiW, AuSn or their eutectic metals.

The LED chip 50B shown in Fig. 10B includes a semiconductor epitaxial layer 55 disposed on one side of the light-transmissive substrate 51. Fig. The semiconductor epitaxial layer 55 may include a first conductive type semiconductor layer 55a, an active layer 55b, and a second conductive type semiconductor layer 55c.

 The LED chip 50B includes first and second electrodes E1 and E2 connected to the first and second conductivity type semiconductor layers 55a and 55c, respectively. The first electrode E1 includes a connection electrode 57a such as a conductive via connected to the first conductive type semiconductor layer 55a through the second conductive type semiconductor layer 55c and the active layer 55b, And a first electrode pad 58a connected to the electrode 57a.

The connection electrode 57a may be surrounded by the insulating portion 53 and electrically separated from the active layer 55b and the second conductivity type semiconductor layer 55c. The connection electrode 57a may be disposed in a region where the semiconductor epitaxial layer 55 is etched. The number, shape, pitch, or contact area of the connection electrode 57a with the first conductive type semiconductor layer 55a can be appropriately designed so as to lower the contact resistance. Further, the connection electrode 57a is arranged in rows and columns on the semiconductor laminate 55, thereby improving current flow. The second electrode E2 may include an ohmic contact layer 57b and a second electrode pad 58b on the second conductive semiconductor layer 55c. First and second electrical connection conductors 59a and 59b may be provided on the first and second electrode pads 58a and 58b. The material of each constitution can be referred to the description of Fig. 10A.

11A and 11B are a plan view and a cross-sectional view, respectively, showing an example of a LED structure that can be employed in an embodiment of the present invention.

Referring to FIGS. 11A and 11B, the LED structure 80B according to the present embodiment has an LED chip 50A having a flip chip structure and a polygonal column extender 60B.

Further, the polymer extender 60B has a left-right asymmetric structure, that is, a shape in which the plane and the cross-section are trapezoidal. Especially, opposite sides SP1, SP2 of the polymer extension portion 60A have different sizes along the electrode array direction. Thus, similar to the example shown in Figs. 10A and 10B, the concave structure of the subpixel is designed to correspond to the shape and size of the polymer extension 60B, thereby arranging the electrodes 59a and 59b of the LED chip 50A The LED structure 80B can be aligned so as to match the arrangement of the predetermined circuit patterns.

FIGS. 12A to 12E are cross-sectional views for explaining a method of transferring an LED chip according to an embodiment of the present invention, and show an example using the LED structure 80A shown in FIGS. 10A and 10B.

First, referring to FIG. 12A, a substrate 110 on which first and second circuit patterns 115a and 115b are formed is provided.

The present process can also be understood as a display manufacturing method, but is not limited thereto and can be understood as a transfer technology of a micro LED chip for a manufacturing process of another illumination device. The substrate 110 employed in the present embodiment can be understood as a circuit board for a lighting apparatus or the like as well as a display panel such as a TFT substrate.

Next, referring to FIG. 12B, a barrier structure 120 defining a desired mounting region C is formed on a substrate 110.

The septum structure 120 employed in this embodiment provides a recess C for receiving the LED structure 80A. The concave portion C has a structure corresponding to the planar shape of the LED structure 80A.

Next, referring to FIG. 12C, the LED structure 80A is aligned in the mounting region C. FIG.

In this alignment process, the LED structure 80A is accommodated in the concave portion C only in a specific direction by the cut surface CP of the polymer extension portion 60A, and the LED structure 80A aligned in that direction has the first And the second electrical connection conductors 59a and 59b may be disposed on the first and second circuit patterns 115a and 115b, respectively. This sorting process can be implemented by one or more than two of the various sorting schemes described in the foregoing embodiments.

Next, referring to FIG. 12D, the polymer extension 60A is removed from the micro LED chip 50A.

The process of removing the polymer extensions 60A can be performed uniformly with respect to the LED structure 80A disposed in the entire mounting area C. [ In this process, only the micro LED chip 50A remains and is disposed in the mounting area, and the first and second electrical connection conductors 59a and 59b of the micro LED chip 50A are electrically connected to the first and second circuit patterns 115a and 115b, 115b. The present process can be carried out by heating to an appropriate temperature.

Next, referring to FIG. 12E, the first and second electrodes 58a and 58b of the micro LED chip 50A are electrically connected to the first and second electrodes 58a 'and 59b' using the first and second electrical connection conductors 59a 'and 59b' Two circuit patterns 115a and 115b, respectively.

This process can be uniformly performed on the entire LED chip 50A similarly to the polymer extender removal process described above. The first and second electrical connection conductors 59a 'and 59b' of the micro LED chip 50 can be melted in the reflow process and bonded to the first and second circuit patterns 115a and 115b have. The reflow process may be performed simultaneously with or concurrently with the process of removing the polymer extender 60A.

The present invention is not limited by the above-described embodiments and the accompanying drawings, but is intended to be limited only by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

Claims (13)

Providing a plurality of LED structures each having an LED chip and a polymer extension applied to the LED chip;
Aligning the plurality of LED structures in desired areas of the display panel, respectively; And
And removing the polymer extensions from the plurality of LED structures after aligning the plurality of LED structures.
The method according to claim 1,
Wherein the polymer extension portion surrounds the LED chip so that the surface of the LED chip on which the electrode is formed is exposed.
3. The method of claim 2,
Each of the desired regions is provided with a circuit pattern,
Wherein aligning the plurality of LED structures comprises aligning the plurality of LED structures such that the exposed electrodes are located in the circuit pattern.
The method of claim 3,
An electrode connecting conductor is disposed on a surface of at least one of the electrode and the circuit pattern,
And melting the electrode connecting conductor such that the electrode is connected to the circuit pattern after the step of removing the polymer extensions.
The method of claim 3,
Wherein at least one of the electrode of the LED chip and the circuit pattern has magnetism so that electrodes of the LED chip are aligned on the circuit pattern in the step of aligning the plurality of LED structures.
The method according to claim 1,
Wherein the desired regions have a concave structure for aligning the plurality of LED structures.
The method according to claim 1,
Wherein the self-assembly monomer is applied to the polymer extensions and the desired regions such that the LED structures are aligned with the desired regions, respectively, in aligning the plurality of LED structures.
The method according to claim 1,
Further comprising the step of providing a solvent containing the plurality of LED structures after forming the plurality of LED structures,
Wherein aligning the plurality of LED structures comprises aligning the plurality of LED structures together with the solvent using a jetting method.
The method according to claim 1,
Wherein aligning the plurality of LED structures is performed using an open sieve.
The method according to claim 1,
Wherein the polymer extender has a spherical shape and has a diameter larger than the length of the LED chip.
The method according to claim 1,
Wherein the polymer extender has an acetal shape,
Wherein the plurality of LED structures have a concave structure for accommodating the plurality of LED structures in the non-spherical shape, respectively, in the step of aligning the plurality of LED structures.
The method according to claim 1,
Wherein the polymer extensions comprise a polymer that is capable of being calcined at a temperature of 300 DEG C or less and wherein the step of removing the polymer extensions comprises heating to the calcineable temperature.
Providing a LED structure including an LED chip having electrodes on at least one side and a polymer extension having a three-dimensional structure surrounding the LED chip such that a surface on which the electrode is formed is exposed;
Aligning the LED structure in a mounting area in which a circuit pattern is formed, the electrodes of the LED chip being disposed on the circuit pattern; And
And heating the LED structure such that the polymer extender is calcined after the step of aligning the LED structure.

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